The invention disclosed herein relates to separating sets of sheet material, for example, sets of paper sheets in paper processing apparatus such as copiers and mailing machines. More particularly, the invention relates to associating strips of material with sets of sheet material to separate the sets.
One technique for separating sets of one or more stacked sheets is to offset the sheet sets. See, for example, U.S. Pat. Nos. 3,860,127 (Fassman) and 4,017,066 (Lasher et al.). One drawback of this sheet set separation technique is that the offset is easily lost and that the once-separated sheet sets are easily mingled.
Another technique positions one or more strips of paper between the adjacent sheet sets to be separated. According to this technique, a strip loosely lies between the first and last sheets of the sets to be separated, i.e., the strip is not adhered or affixed to the sheets in any way and becomes engaged solely by virtue of being between adjacent sheets of adjacent sets. See, for example, U.S. Pat. Nos. 2,052,615 (Foellmer), 2,795,172 (Hanson) 2,837,016 (Jezierski) and 3,458,186 (Schmidt). One drawback of this technique is that the strips easily fall out or the strips are easily moved so they are not easily visible from the exterior of a stack of sheet sets. Typically, this technique involves advancing the strip from a roll thereof, inserting the strip adjacent the first or last sheet of a set, severing the strip from the roll and moving the next sheet from the adjacent set into position adjacent the inserted strip, although not necessarily in the order described.
In the patents cited above in connection with positioning a strip between sets of sheets to be separated, the strip is advanced from a roll thereof and severed therefrom. U.S. Pat. Nos. 2,621,737 (Ledig), 3,128,219 (Cummings), 3,902,646 (Kuhns), 3,911,517 (Davis) and 4,611,736 (Gavronsky et al.) disclose strip or tape dispensing apparatus in which a strip or tape is withdrawn from a roll, severed therefrom and adhered to a sheet. In these four patents, however, the strip is adhered to a sheet of a sheet set, not for separating a sheet set, but for binding the sheets of a set together, or is adhered to a sheet for other reasons. U.S. Pat. No. 4,586,232 (Ohmura et al.) discloses wrapping bundles with shrink wrapping film withdrawn and severed from a roll thereof, in which the film is positioned in the path of an advancing bundle where it is engaged by and drawn around the advancing bundle.
Co-pending U.S. patent application Ser. No. (632,805), titled "SHEET SET SEPARATION USING FOLDED SHEETS", filed 12/24/90, which is assigned to the assignee of this application, discloses apparatus for folding a strip of paper about the edge of a set of stacked sheets of paper to separate that sheet set from other adjacent sheet sets. The disclosure of said application is incorporated herein by reference. As disclosed in the co-pending application, the folded strip of paper has strip portions extending substantial distances along major sides of the sheet set. Such a folded strip separator reduces the risk that the strip will be moved between adjacent sheet sets so as not to be visible from the side of a stack of sheets sets and also reduces the risk that the strip will be separated altogether from the sheet set.
In the folding apparatus disclosed in the co-pending application, as illustrated in FIGS. 1, 2 and 4 in this application, a strip of paper 33 is held in the path of an advancing sheet set 16 which engages the strip and carries it into the folding nip 60 formed by a pair of opposed belt conveyers, which folds the strip 33 about the edge 38 of the sheet set 16 as the sheet set advances into and through nip 60. The width of the folding nip 60 is approximately the width of the belts 65 and 66 formed by the upper and lower belt conveyers, respectively. While the quality of the fold made by such apparatus of paper strips having a width not substantially wider than the width of the belts was found to be entirely satisfactorily, it was found also that the quality of the fold of paper strips having widths substantially wider than the width of the belts was not entirely satisfactory. It was also found that the quality of the fold of a strip having approximately the width of the belts which was fed to the folding nip skewed was also not entirely satisfactory. The invention disclosed in this application addresses those drawbacks.